In plain words
You must see that you cause no hurt of any kind to anyone. That is why help ever, hurt never. It has been said. We must follow discipline on the path of doing good to others. That is why start early, drive slowly, reach safely. It has been said.
Discipline is needed from a tender age. Not only for children, but for officials too, for teachers too, for citizens too, this discipline is essential. How we should show respect when we see elders, how we should sit in front of whom: in such small matters too we must keep discipline well. Many small children sit. Like an arrow of some kind. You should not sit this way. You must sit properly. For only when the spinal column is straight does our thought go straight to the Buddhi and reach it. In a very short time we can gain concentration. The spinal column has thirty-three rings. Between nine and twelve of them lies the suṣumnā nāḍī. If it is in its proper order there, the kuṇḍalinī power goes straight to the sahasrāra lotus and reaches it. Many who know the practice of yoga speak in such words, saying that in the mūlādhāra centre there is a serpent called kuṇḍalinī, and that it gradually rises upward and reaches the sahasrāra cakra. When is this kuṇḍalinī power in the mūlādhāra centre? Many people practise prāṇāyāma. During this prāṇāyāma they hold the breath and work the kuṇḍalinī. Because the breath is held, because there is no air at the mūlādhāra cakra, it goes upward in search of air. It is not a serpent. It is only air. It gradually rises through these thirty-three openings. If we want to know this kuṇḍalinī power, we must keep our spine straight. That is why those who practise yoga sit straight. That is very good. It gives memory. It brings calm. So even the way we sit is discipline.
For this discipline to go well in us, there are certain kinds of purity. First of all we must purify our body. What is this purity?